Speedometer temperature compensator



DCC. 29, 1931G ZUBATY 1,838,896

SPEEDOMETER TEMPERATURE COMPENSATOR Filed Sept. 29, 1928 ,Inpnpnar'n'u'1' i' T20 shunt.

Patented Dec. 29, Y1931-V UNITEnsTATQESs instala-ir;orificef;

.'rosnrn ZUBATY, or FLINT, n icHieAN, AssIGfNoR'ro A C srm` rLuG coMrANY, oF n i FLINT, irriciireamn COMPANY or :timmeren4` r Y s1.lnanoirm'rEn. TEMPERATURE coMrENsA'ron A Application filed September 29,1928. Serial' No. 309,283.

This invention relates to measuring instruments and has .been Vdesigned particular- :ly asian improved speedometer for use on motor vehicles. Y A 5 VAn object of the invention is to render the readings of such an` instrumentv accurate at all temperatures. Y. I Another object is to attain the desired end by the use of temperature. correcting means employing no movable parts.

As a furtherobject the invention is de,- signed for vuse particularly with a specific v type of speedometer wherein all supporting parts are made from inexpensive stampings, 1*-"15 and wherein a guard is used around the speed cup to support certain of the elements of the instrument, this guard4 constituting a convenient member to co-operate withthe compensator in making an Yeliicient magnetic Other objects and advantages will be un- -dersto'od from the following specification. In the drawings:

' Fi ure 1 is a vertical sectional viewof a r 'fi-25 spee ometer with the invention applied,

parts beingshown in elevation, parts broken HJVlf1-5,`parts in section; l Y Y with Vlbeing'shown inposition; and Y v Y Figure 3'isfa top plan 'view showing the case in section andthe mounting plate in ele- S j Y The speedometer shown in the drawings vis housed in acasing 9. To this casing is secured a mounting plate Q10' which supports the odometer unit shafts v'11 and12. These shafts are-journalled between side wings 13 and 14, stamp`ed and angularly turned from the vmounting plate 10. YThe Y odometer wheels are assembled on the shaftsV 11 and 12 and are driven in the well-known man ner by star pinions. These star pinions are not illustrated, being preferablyjwithin the contour of the gure wheels which later are provided in awell-knownway withlinternal the case removed the A"compensator units `gear members. Thestar piniOns-aresup-V ported lby stampi'ngs V15 which are suitably secured and held ,stationary by ymeans of shafts 16 and 17. Shaft 16 is j ournalled be- Secured to the mounting platey and supported by it is a speedometer mechanismfsupporting frame 20. This frame also is formed tween'the wing members 13 and 14, and shaft from a stamping. Mounted between tongues 21 and 22 is a drive bushing kbearing 23 in which is journalled the drive bushing 24;. The lower end of ,this Vbushing is drivingly connected to the main flexiblecable 25. The driving connectionmay include non-ci`rcular portions, not shown in the drawing, or other convenient means may be employed. The; Vdrivebushing projects upwardly from` the bearing and formed on the bushing is aneccentric or cam 26, upon which is journalled a'pawl 27 which drives the double reduction ratchet wheels 28, these havinga knownform* of construction, which ratchet wheels in turn ,drive the gear 29, the lattermeshingwith gear 30` to drive the` season mileage record-4 ing figure wheels 31 Yon shaft 11. The trip -wheels 32011 shafty12 are; driven byy gear. -ing'between shafts 11 and 12, including an intermediate gear preferably mounted on Y Figure 2Ais a rear-elevationof Figure 1V shaft 1111. `As this construction is wellknown, it is not. fully illustrated.

Above the upper end of the drive bush-,

ing is a1 guard member v33, preferably of steel. `This guard memberis mounted upon and secured to vang'ularly` turned horizontal wing members 34 and 35 constituting apart of, frame-20 which,'in this way, actsl as a;

y Fixedly mounted upon .upperfend `of the drive bushing by meansV of riveting over as 'at 39 is a rotating magnet40. This magnet is cross-shapedpas shown-by dotted linesV inFigure3, Vand there are member-'S41 which bridge the magnet gaps andare suitably lriveted Vto `the' magnet.

A vspeed cup 421is centrally centered meansof the usual speed-cup spindler43.'

4tened-,Sand 'clamped thereon by A thumb nut 52.

` Projecting downwardly from part 20 isa tongue 53. This tongue acts asa support `for This spindle may be journalled in the usual way, preferably its lower end being received in bearings in the end of drive bushing 24 and its upper end extending through suitable bearings in the guard member 33. As this is a conventional method for mountingthe speedcup spindle, it is not illustrated. in detail.

Above theguard 33, the upper end of the spindle is provided with'a hub member 44 lto which is fixed one end of a' coil hair spring 45, the other end of the springbeing liXed to an upwardly projecting ear 46 stamped from the guard 33. y A

F or the purpose of limiting the rotation of "the speedccup, an ear 47 is stamped from member y33 and'angularly turned downwardly to project into the path of a similarly stamped ear upwardly directed from the speed cup.

A ferrule 48 is employed at the point of entrance of. the-flexible driving cable 25. To the ferrule at the lower end is lined an armoringcable49 for protecting the rotating cable 25. Preferably, although not shown in l the drawing, the driveca-ble 25 will be provided with a bushing, the bushing having a flange to engage a suitable shoulder within the ferrule whereby the backward movement ofthe cable 25 is prevented and the driving i connection between parts 25 and 24 is mamtained. This structure, not constituting a part of this invention, is not illustrated.

Fixed to the ferrule 4S is a clamping member50 which is bifurcated at its end remote from the errule. The bifurcated end yolres over a fastening screw 5l and is securely fasmeans Yof a a reset stem 54. y The reset stem does not constitute any part of thisy invention and its relation to the .trip wheels is as usual in odomor riveting is a temperature compensator 55. This .compensator projects downwardly and is angularly bent to` project towards. the magnet and then again angularly turned so that.

its end is in close proximity to the magnet and, consequently, directly within the magnetic lield.

Because' of the composition of the metal .member 55, which consists of'a nickel-copper alloy having the property of magnetic conductivity at low temperaturesand changingto practically no conductivitylat high temperatures, magnetic current will be shunted yor'otherwisediverted to the steel guard 33l through the member at low temperatures due to the increased conductivity of the member 55 to thereby decreasethe magnetic flow n or flux ofthe magnetic field established by i, fthe `rotating magnet 40. 0n the other hand,y

the How or flux of the magnetic current in the magnetic field will be increased proportionately to the low conductivity of member 55 at high temperatures, thereby retaining the magnetic flux within the magnetic field. By this means, the effects of temperature changes .are offset andthe instrument rendered accurate at all temperatures.

A member 56 is shown in the drawing riveted to frame 2O andA also extendedto a position adjacent the magnet 40. This member 56 is also a nickel-copper alloy and its function is precisely the same as that of member 55., It will be understood that if parts 2O and 33 are both of steel and if it be so desired, both members 55 and 56 may be used. However, under such circumstances, it is believed that one such member, y55 or 56, will be suliicient. It should be.. further stated that in the event that part 33 or 2O should be of other thanzmagnetic material, one only of the members 55 or 56 will be used, the member used being associated with that part, 33 or 20, which is of magnetic material.

By the construction` above outlined, there has been produced a speedometer of very `simple design in which the mostidesirable features of speedometers heretofore known have been incorporated. The. instrument is rigid, sturdy and durable and has, neverthe-i less, been made of stampings and without any expensivediecast parts.- The mainmounting plateAlO directly supports the odometer mechanism `and the speedometer supporting mechanism, also a stamping, is secured to the first framer 'Y The 4dierent f operatingA units have` been combined in a way to simplify-the-structure without, decreasinggits elficiency-in fact, the

emcienct operation of the `unit as a wholezhas' been` increased.' .The assembly is rendered very compact and reducedin weight. There is a substantial reduction Vinmachining operations,` particularly in the relatively-expensive operations lsueltas die casting` and worm gear cutting. Thewormgearing heretofore used in speedometers has been altogether eliminated and the ratchet drive isdirectly mounted on the driving bushing, this,` being made possible with the useof, the doublereduction ratchet mechanism. The magnet is directly 'mounted on the bushing, thus Vdispensing with the rotor.- There is a lsimplified mounting means for the speed cup in which the conventional jewel frame is displaced and' the guard -member `which supports the-tem;

perature compensatorV is' used. This guard fmember alsoV affords theimeans for connecting thejend ofthe hair spring.A

A,It is thus `seenthatfby `providing stamp-A `ings for all theV frame membersA such as mounting` plate, supporting frame and guard unit, as well asfthe casing itself, a speedometer fis-produced 1 having uniform strengthi whichv is carried `throughout `as. a

unit. There are less parts to get out of order and the mechanism is greatly simplied. There is, in consequence, a high degree of efflciency and accuracy which results are obtained with a considerable lower produc-v tion cost in manufacture and assembly.l

I claim:

In a measuring instrument, a rotary magnet, a rotary speed cup surrounding said mag-f,

net, a cup-shaped guard of magnetic material surrounding said speed cup, a temperature compensator having its magnetic conductivity decreasing With increasing temperatures, said compensator being secured to said guard and extended toV a position adjacent said magnet. Y

In testimony whereof I aiix my signature.

JOSEPH ZUBATY. 

